Fluid Collection Canister Including Canister Top with Filter Membrane and Negative Pressure Wound Therapy Systems Including Same

ABSTRACT

A fluid collection canister including a chamber to collect fluids and a canister top disposed over the chamber. The canister top includes a bottom side facing into the chamber, including first and second ribs disposed thereon, a filter membrane attached to the first and second ribs, a first port to communicate with the chamber and a pressure source external to the chamber, and a second port to communicate with the chamber and a sensor external to the chamber. The first port is in fluid communication with a first area, which is bounded by the filter membrane, the first and second ribs and the bottom side of the canister top. The second port is in fluid communication with a second area, which is bounded by the filter membrane, the second rib and the bottom side of the canister top.

BACKGROUND

1. Technical Field

The present disclosure relates to negative pressure wound therapysystems and, more particularly, to a fluid collection canister includinga canister top with a filter membrane and negative pressure woundtherapy systems including the same.

2. Discussion of Related Art

Negative pressure therapy, also known as suction or vacuum therapy, hasbeen used in treating and healing wounds. Treating an open wound byapplying negative pressure, e.g., reduced or sub-atmospheric pressure,to a localized reservoir over a wound has been found to assist inclosing the wound by increasing blood circulation at the wound area,stimulating the formation of granulation tissue and promoting themigration of healthy tissue over the wound. Negative pressure therapymay also inhibit bacterial growth by drawing wound fluids from the woundsuch as exudate, which may tend to harbor bacteria. Negative pressuretherapy can thus be applied as a healing modality for its antiseptic andtissue regeneration effects. This technique has proven effective fortreating a variety of wound conditions, including chronic orhealing-resistant wounds and ulcers, and is also used for other purposessuch as post-operative wound care.

Generally, negative pressure therapy provides for a wound covering to bepositioned over the wound to facilitate suction at the wound area. Aconduit is introduced through the wound covering to provide fluidcommunication to an external vacuum source, such as a hospital vacuumsystem or a portable vacuum pump. Atmospheric gas, wound exudate orother fluids may thus be drawn from the reservoir through the fluidconduit to stimulate healing of the wound. Generally, a fluid collectioncanister for collecting fluids aspirated from the wound is positioned inthe suction line between the wound covering and the vacuum source.Exudate drawn from the reservoir through the fluid conduit may thus bedeposited into the collection canister.

During a treatment, vacuum levels within a negative pressure woundtherapy system may be monitored and controlled. There are a variety ofpressure detecting devices such as pressure gages, switches, transducersand transmitters that can be used for measuring vacuum levels. Anegative pressure wound therapy system may not function properly whenfluid contamination of various components degrades the capability toaccurately measure vacuum levels in the negative pressure wound therapysystem. When the collection canister is tilted from upright, fluid mayocclude a filter in communication with a pressure detecting device,preventing accurate measurement of vacuum levels in the negativepressure wound therapy system. This may cause the negative pressurewound therapy system to react as if a pneumatic leak is present in thesystem and may cause vacuum level within the collection canister to gouncontrolled, which may result in improper therapy to the patient.

A mechanism for preventing overfilling of the collection canister mayprevent fluid contamination of various components of the negativepressure wound therapy system and help to prevent spillage or leakage ofexudate. During a treatment, the collection canister may be preventedfrom overfilling by a hydrophobic filter at the top of the collectioncanister that shuts off the air flow to the vacuum source when thecollection canister is full. In portable negative pressure wound therapysystems, which may be worn or carried by a patient, there is alikelihood that the apparatus will shift into various orientations whilethe patient is ambulating, allowing exudate to occlude the filter whenthe collection canister is not full. Negative pressure therapy may bediscontinued or interrupted inadvertently when the filter is occludedduring patient ambulation or when the collection canister is tippedover. There is a need for a negative pressure wound therapy system thatpermits accurate measurement of vacuum levels in the negative pressurewound therapy system and is capable of providing negative pressuretherapy for varied orientations of the collection canister.

SUMMARY

The present disclosure relates to a fluid collection canister includinga chamber to collect fluids and a canister top disposed over thechamber. The canister top includes a bottom side facing into thechamber, including first and second ribs disposed thereon, a filtermembrane attached to the first and second ribs, a first port tocommunicate with the chamber and a pressure source external to thechamber, and a second port to communicate with the chamber and a sensorexternal to the chamber. The first port is in fluid communication with afirst area, which is bounded by the filter membrane, the first andsecond ribs and the bottom side of the canister top. The second port isin fluid communication with a second area, which is bounded by thefilter membrane, the second rib and the bottom side of the canister top.

The present disclosure also relates to a portable negative pressurewound therapy apparatus including a dressing assembly for positioningover a wound to apply a negative pressure to the wound and a canisterassembly in fluid communication with the dressing assembly. The canisterassembly includes a control unit, a vacuum source disposed in thecontrol unit, a pressure sensor in communication with the control unit,and a collection canister. The collection canister includes a chamber tocollect wound fluids from the dressing assembly, a canister top disposedover the chamber, the canister top including a bottom side facing intothe chamber, the bottom side including first and second ribs disposedthereon, an inlet port in fluid communication with the dressing assemblyto introduce the wound fluids from the dressing assembly into thechamber, a suction port located on the canister top to communicate withthe chamber and the vacuum source, a pressure sensor port located on thecanister top to communicate with the chamber and the pressure sensor,and a filter membrane attached to the first and second ribs. Thepressure sensor port is in fluid communication with a first chamber,which is bounded by the filter membrane, the first and second ribs andthe bottom side of the canister top. The suction port is in fluidcommunication with a second chamber, which is bounded by the filtermembrane, the second rib and the bottom side of the canister top.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently disclosed negative pressure woundtherapy systems will become apparent to those of ordinary skill in theart when descriptions of various embodiments thereof are read withreference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram of an embodiment of a negative pressurewound therapy system in accordance with the present disclosure;

FIG. 2 is a schematic diagram of an embodiment of a negative pressurewound therapy system including a canister assembly in accordance withthe present disclosure;

FIG. 3 is a schematic diagram of the canister assembly of the negativepressure wound therapy system illustrated in FIG. 2;

FIG. 4 is a cross-sectional view of the collection canister of thecanister assembly shown in FIG. 2 taken along the lines 4-4;

FIG. 5 is a bottom view of the canister top of the collection canistershown in FIG. 4;

FIG. 6 is a schematic diagram of another embodiment of a canister top ofa collection canister in accordance with the present disclosure;

FIG. 7 is a schematic diagram of the canister top illustrated in FIG. 6,shown with a filter membrane, in accordance with the present disclosure;

FIG. 8 is a schematic diagram of the canister top illustrated in FIG. 7with the outer sealing rib and the isolating rib of FIG. 6 shown inphantom;

FIG. 9 is a cross-sectional view of another embodiment of a collectioncanister in accordance with the present disclosure;

FIG. 10 a bottom view of the canister top of the collection canistershown in FIG. 9;

FIG. 11 is a schematic diagram of the canister top illustrated in FIG.10, shown with a filter membrane, in accordance with the presentdisclosure; and

FIG. 12 is a schematic diagram of the canister top illustrated in FIG.11 with the outer sealing rib and the isolating rib of FIG. 10 shown inphantom.

DETAILED DESCRIPTION

Various embodiments of the present disclosure provide negative pressurewound therapy systems (or apparatus) including a collection canisterhaving a chamber to collect wound fluids and a canister top disposedover the chamber. Embodiments of the presently disclosed negativepressure wound therapy systems are generally suitable for use inapplying negative pressure to a wound to facilitate healing of the woundin accordance with various treatment modalities. Embodiments of thepresently disclosed negative pressure wound therapy systems are entirelyportable and may be worn or carried by the user such that the user maybe completely ambulatory during the therapy period. Embodiments of thepresently disclosed negative pressure wound therapy apparatus andcomponents thereof may be entirely reusable or may be entirelydisposable after a predetermined period of use or may be individuallydisposable whereby some of the components are reused for a subsequenttherapy application. Embodiments of the presently disclosed collectioncanisters interface with a control unit to allow suction from a vacuumsource and to allow monitoring of the canister vacuum level.

Hereinafter, embodiments of the presently disclosed negative pressurewound therapy systems will be described with reference to theaccompanying drawings. Like reference numerals may refer to similar oridentical elements throughout the description of the figures. As it isused in this description, “wound exudate”, or, simply, “exudate”,generally refers to any fluid output from a wound, e.g., blood, serum,and/or pus, etc. As it is used in this description, “fluid” generallyrefers to a liquid, a gas or both. As it is used in this description,“pressure” generally refers to positive pressure, negative pressure orboth. As it is used in this description, “pressure” is measured relativeto the ambient atmospheric pressure. Thus, positive pressure refers topressure greater than the ambient atmospheric pressure, and negativepressure (or vacuum) refers to pressure less than the ambientatmospheric pressure. As used herein, “transmission line” generallyrefers to any transmission medium that can be used for the propagationof signals from one point to another.

Referring to FIG. 1, a negative pressure wound therapy apparatusaccording to an embodiment of the present disclosure is depictedgenerally as 10 for use on a wound bed “w” surrounded by healthy skin“s”. Negative pressure wound therapy apparatus 10 includes a wounddressing 12 positioned relative to the wound bed “w” to define a vacuumchamber 14 about the wound bed “w” to maintain negative pressure at thewound area. Wound dressing 12 includes a contact layer 18, a woundfiller 20 and a wound cover 24.

Contact layer 18 is intended for placement within the wound bed “w” andmay be relatively non-supportive or flexible to substantially conform tothe topography of the wound bed “w”. A variety of materials may be usedfor the contact layer 18. Contact layer 18 selection may depend onvarious factors such as the patient's condition, the condition of theperiwound skin, the amount of exudate and/or the condition of the woundbed “w”. Contact layer 18 may be formed from perforated film material.The porous characteristic of the contact layer 18 permits exudate topass from the wound bed “w” through the contact layer 18. Passage ofwound exudate through the contact layer 18 may be substantiallyunidirectional such that exudate does not tend to flow back into thewound bed “w”. Unidirectional flow may be encouraged by directionalapertures, e.g., apertures positioned at peaks of undulations orcone-shaped formations protruding from the contact layer 18.Unidirectional flow may also be encouraged by laminating the contactlayer 18 with materials having absorption properties differing fromthose of the contact layer 18, or by selection of materials that promotedirectional flow. A non-adherent material may be selected for formingthe contact layer 18 such that the contact layer 18 does not tend tocling to the wound bed “w” or surrounding tissue when it is removed. Oneexample of a material that may be suitable for use as a contact layer 18is commercially available under the trademark XEROFLOW® offered by TycoHealthcare Group LP (d/b/a Covidien). Another example of a material thatmay be suitable for use as the contact layer 18 is the commerciallyavailable CURITY® non-adherent dressing offered by Tyco Healthcare GroupLP (d/b/a Covidien).

Wound filler 20 is positioned in the wound bed “w” over the contactlayer 18 and is intended to transfer wound exudate. Wound filler 20 isconformable to assume the shape of any wound bed “w” and may be packedup to any level, e.g., up to the level of healthy skin “s” or tooverfill the wound such that wound filler 20 protrudes over healthy skin“s”. Wound filler 20 may be treated with agents such aspolyhexamethylene biguanide (PHMB) to decrease the incidence ofinfection and/or other medicaments to promote wound healing. A varietyof materials may be used for the wound filler 20. An example of amaterial that may be suitable for use as the wound filler 20 is theantimicrobial dressing commercially available under the trademarkKERLIX™ AMD™ offered by Tyco Healthcare Group LP (d/b/a Covidien).

Cover layer 24 may be formed of a flexible membrane, e.g., a polymericor elastomeric film, which may include a biocompatible adhesive on atleast a portion of the cover layer 24, e.g., at the periphery 26 of thecover layer 24. Alternately, the cover layer 24 may be a substantiallyrigid member. Cover layer 24 may be positioned over the wound bed “w”such that a substantially continuous band of a biocompatible adhesive atthe periphery 26 of the cover layer 24 forms a substantially fluid-tightseal with the surrounding skin “s”. An example of a material that may besuitable for use as the cover layer 24 is commercially available underthe trademark CURAFORM ISLAND® offered by Tyco Healthcare Group LP(d/b/a Covidien).

Cover layer 24 may act as both a microbial barrier and a fluid barrierto prevent contaminants from entering the wound bed “w” and to helpmaintain the integrity thereof.

In one embodiment, the cover layer 24 is formed from a moisture vaporpermeable membrane, e.g., to promote the exchange of oxygen and moisturebetween the wound bed “w” and the atmosphere. An example of a membranethat may provide a suitable moisture vapor transmission rate (MVTR) is atransparent membrane commercially available under the trade namePOLYSKIN® II offered by Tyco Healthcare Group LP (d/b/a Covidien). Atransparent membrane may help to permit a visual assessment of woundconditions to be made without requiring removal of the cover layer 24.

Wound dressing 12 may include a vacuum port 30 having a flange 34 tofacilitate connection of the vacuum chamber 14 to a vacuum system.Vacuum port 30 may be configured as a rigid or flexible, low-profilecomponent and may be adapted to receive a conduit 36 in a releasable andfluid-tight manner. An adhesive on at least a portion of the undersideof the flange 34 may be used to provide a mechanism for affixing thevacuum port 30 to the cover layer 24. The relative positions, sizeand/or shape of the vacuum port 30 and the flange 34 may be varied froman embodiment depicted in FIG. 1. For example, the flange 34 may bepositioned within the vacuum chamber 14 such that an adhesive on atleast a portion of an upper side surface of the flange 34 affixes thevacuum port 30 to the cover layer 24. A hollow interior portion of thevacuum port 30 provides fluid communication between the conduit 36 andthe vacuum chamber 14. Conduit 36 extends from the vacuum port 30 toprovide fluid communication between the vacuum chamber 14 and the vacuumsource 40. Alternately, the vacuum port 30 may not be included in thedressing 12 if other provisions are made for providing fluidcommunication with the conduit 36.

Any suitable conduit may be used for the conduit 36, including conduitfabricated from flexible elastomeric or polymeric materials. In thenegative pressure wound therapy apparatus 10 illustrated in FIG. 1, theconduit 36 includes a first conduit section 36A, a second conduitsection 36B, a third conduit section 36C and a fourth conduit section36D. The first conduit section 36A extends from the vacuum port 30 andis coupled via a fluid line coupling 100 to the second conduit section36B, which extends to the collection canister 38. The third conduitsection 36C extends from the collection canister 38 and is coupled viaanother fluid line coupling 100 to the fourth conduit section 36D, whichextends to the vacuum source 40. The shape, size and/or number ofconduit sections of the conduit 36 may be varied from the first, second,third and fourth conduit sections 36A, 36B, 36C and 36D depicted in FIG.1.

The first, second, third and fourth conduit sections 36A, 36B, 36C and36D of the conduit 36 may be connected to components of the apparatus 10by conventional air-tight means, such as, for example, friction fit,bayonet coupling, or barbed connectors. The connections may be madepermanent. Alternately, a quick-disconnect or other releasableconnection means may be used to provide some adjustment flexibility tothe apparatus 10.

Collection canister 38 may be formed of any type of container that issuitable for containing wound fluids. For example, a semi-rigid plasticbottle may be used for the collection canister 38. A flexible polymericpouch or other hollow container body may be used for the collectioncanister 38. Collection canister 38 may contain an absorbent material toconsolidate or contain the wound fluids or debris. For example, superabsorbent polymers (SAP), silica gel, sodium polyacrylate, potassiumpolyacrylamide or related compounds may be provided within collectioncanister 38. At least a portion of canister 38 may be transparent orsemi-transparent, e.g., to permit a visual assessment of the woundexudate to assist in evaluating the color, quality and/or quantity ofexudate. A transparent or semi-transparent portion of the collectioncanister 38 may permit a visual assessment to assist in determining theremaining capacity or open volume of the canister and/or may assist indetermining whether to replace the collection canister 38.

The collection canister 38 is in fluid communication with the wounddressing 12 via the first and second conduit sections 36A, 36B. Thethird and fourth conduit sections 36C, 36D connect the collectioncanister 38 to the vacuum source 40 that generates or otherwise providesa negative pressure to the collection canister 38. Vacuum source 40 mayinclude a peristaltic pump, a diaphragmatic pump or other suitablemechanism. Vacuum source 40 may be a miniature pump or micropump thatmay be biocompatible and adapted to maintain or draw adequate andtherapeutic vacuum levels. The vacuum level of subatmospheric pressureachieved may be in the range of about 20 mmHg to about 500 mmHg. Inembodiments, the vacuum level may be about 75 mmHg to about 125 mmHg, orabout 40 mmHg to about 80 mmHg. One example of a peristaltic pump thatmay be used as the vacuum source 40 is the commercially availableKangaroo PET Eternal Feeding Pump offered by Tyco Healthcare Group LP(d/b/a Covidien). Vacuum source 40 may be actuated by an actuator (notshown) which may be any means known by those skilled in the art,including, for example, alternating current (AC) motors, direct current(DC) motors, voice coil actuators, solenoids, and the like. The actuatormay be incorporated within the vacuum source 40.

In embodiments, the negative pressure wound therapy apparatus 10includes one or more fluid line couplings 100 that allow for selectablecoupling and decoupling of conduit sections. For example, a fluid linecoupling 100 may be used to maintain fluid communication between thefirst and second conduit sections 36A, 36B when engaged, and mayinterrupt fluid flow between the first and second conduit sections 36A,36B when disengaged. Thus, fluid line coupling 100 may facilitate theconnection, disconnection or maintenance of components of the negativepressure wound therapy apparatus 10, including the replacement of thecollection canister 38. Additional or alternate placement of one or morefluid line couplings 100 at any location in line with the conduit 36 mayfacilitate other procedures. For example, the placement of a fluid linecoupling 100 between the third and fourth conduit sections 36C, 36D, asdepicted in FIG. 1, may facilitate servicing of the vacuum source 40.

Referring to FIG. 2, the negative pressure wound therapy system showngenerally as 200 includes a dressing assembly 210, a wound port assembly220, an extension assembly 230 and a canister assembly 240. Dressingassembly 210 is positioned relative to the wound area to define a vacuumchamber about the wound area to maintain negative pressure at the woundarea. Dressing assembly 210 may be substantially sealed from extraneousair leakage, e.g., using adhesive coverings. Wound port assembly 220 ismounted to the dressing assembly 210. For example, wound port assembly220 may include a substantially continuous band of adhesive at itsperiphery for affixing the wound port assembly 220 to the dressingassembly 210. Extension assembly 230 is coupled between the wound portassembly 220 and the canister assembly 240 and defines a fluid flow pathbetween the wound port assembly 220 and the canister assembly 240. Ahollow interior of the wound port assembly 220 provides fluidcommunication between the extension assembly 230 and the interior of thedressing assembly 210. Dressing assembly 210 and the wound port assembly220 shown in FIG. 2 are similar to components of the wound dressing 12of FIG. 1 and further description thereof is omitted in the interests ofbrevity.

Canister assembly 240 includes a control unit 246 and a collectioncanister 242 disposed below the control unit 246. Control unit 246 andthe collection canister 242 may be releasably coupled. Mechanisms forselective coupling and decoupling of the control unit 246 and thecollection canister 242 include fasteners, latches, clips, straps,bayonet mounts, magnetic couplings, and other devices. Collectioncanister 242 may include any container suitable for containing woundfluids. In embodiments, the canister assembly 240 is configured tosubstantially prevent escape of exudate into the user's immediateenvironment when the collection canister 242 is decoupled from thecontrol unit 246.

In one embodiment, the negative pressure wound therapy system 200 iscapable of operating in a continuous mode or an alternating mode. In thecontinuous mode, the control unit 246 controls a pump (e.g., suctionpump 360 shown in FIG. 3) to continuously supply a selected vacuum levelat the collection canister 242 to create a reduced pressure state withinthe dressing assembly 210. In the alternating mode, the control unit 246controls the pump to alternating supply a first negative pressure, e.g.,about 80 mmHg, at the collection canister 242 for a preset fixed amountof time and a second negative pressure, e.g., about 50 mmHg, at thecollection canister 242 for a different preset fixed amount of time.

In general, the output of the pump is directly related to the degree ofair leakage in the negative pressure wound therapy system 200 and theopen volume in the collection canister 242. If there is sufficient airleakage in the system 200, e.g., at the dressing assembly 210, the pumpcan remain on continuously and the control unit 246 can control negativepressure at the collection canister 242 by adjusting the pump speed.Alternatively, if there is not sufficient air leakage in the system 200to permit the pump to remain on continuously, the control unit 246 cancontrol negative pressure at the collection canister 242 by turning thepump on and off, e.g., for non-equal on/off periods of time.

Control unit 246 responds to various sensed events by signaling alarms.Various types of conditions may be signaled by alarms. In embodiments,control unit 246 is capable of signaling alarms for failed pressuresensor condition, use odometer expired condition, watchdog resetcondition, failed pump condition, leak condition, replace canistercondition, excessive vacuum condition, failed LEDs condition, lowbattery condition, very low battery condition, and failed batterycondition. Priority levels may be associated with alarms. Inembodiments, the priority levels of alarms are low priority alarm,medium priority alarm, and system alarm (highest priority). Low priorityalarms, when triggered, may be continuously indicated. Medium priorityalarms and system alarms, when triggered, may have a flashingindication.

Control unit 246 may stop operation of the pump (e.g., suction pump 360shown in FIG. 3) in response to an alarm, e.g., depending on alarm typeand/or priority level. In embodiments, the control unit 246 stopsoperation of the pump in response to system alarms, e.g., failedpressure sensor system alarm, use odometer expired system alarm,watchdog reset system alarm, failed pump system alarm, excessive vacuumsystem alarm, and/or failed LEDs system alarm.

If an air leak develops in the negative pressure wound therapy system200, e.g., at the dressing assembly 210, for which the control unit 246cannot compensate by increasing the pump speed, the control unit 246 mayindicate an alarm. For example, the control unit 246 may indicate a leakalarm after two consecutive minutes of operation in which the vacuumlevel is below the current set point (or below the minimum level of aset point range).

Audible indicatory means may also be incorporated or associated with thecontrol unit 246 to notify the user of a condition, e.g., leak, canisterassembly tip, failed pressure sensor, failed pump, excessive vacuum, orlow battery conditions. The audio indication for some alarm types can bepaused by pressing a pause alarm button (not shown).

In embodiments, the control unit 246 includes a user interface (notshown). Control unit 246 also includes a processor (e.g., 310 shown inFIG. 3). A pressure sensor (e.g., 340 shown in FIG. 3) is electricallycoupled to the processor. The user turns ON the canister assembly 240 bypressing a power button (not shown). When the power button is pressed,the control unit 246 performs a series of internal checks during powerup. In one embodiment, after successfully completing the power-up tasks,the control unit 246 turns on the pump 360 using the stored settings. Atinitial activation of the canister assembly 240, the stored settings arethe default settings. In one embodiment, the default settings forcontrolling the pump 360 are 80 mmHg and continuous mode. In oneembodiment, the currently stored vacuum level setting can be altered bythe user, e.g., to 50 mmHg. In one embodiment, the currently stored modesetting can be altered by the user, e.g., to an alternating mode.

Canister assembly 240 may be constructed from a variety of materialssuch as Lucite™ polycarbonate, metals, metal alloys, plastics, or otherdurable materials capable of withstanding forces applied during normaluse, and may have some capability of withstanding possibly excessiveforces resulting from misuse. Collection canister 242 may include awindow (not shown) with fluid level markings or graduations forpromoting visual assessment of the amount of exudate contained withinthe collection canister 242. A transparent or partially transparentcollection canister 242 may thus assist in determining the remainingcapacity of the collection canister 242 and/or when the collectioncanister 242 should be replaced.

Referring to FIG. 3, an embodiment of the canister assembly 240illustrated in FIG. 2 is shown and includes a control unit 246 and acollection canister 242. In embodiments, the canister assembly 240 iscoupled via an extension assembly 230 to a dressing assembly (e.g., 12shown in FIG. 1) to apply negative pressure to a wound to facilitatehealing of the wound in accordance with various treatment modalities.

Collection canister 242 includes a chamber 335 to collect wound fluidsfrom the dressing assembly, a canister top 336 disposed over thechamber, a suction port 374 to communicate with the chamber 335 and thesuction pump 360, a canister inlet port 334 to introduce the woundfluids from the dressing assembly into the chamber 335, and a pressuresensor port 396 to communicate with the chamber 335 and the pressuresensor 340. Suction port 374 may include an o-ring on the outsidediameter to provide for appropriate sealing to the suction port when thecollection canister 242 and control unit 246 are attached together.Collection canister 242 may be disposable. Collection canister 242 maycontain a liner that is disposable.

In embodiments, the canister inlet port 334 is coupled to the extensionassembly 230. Canister inlet port 334 may be connectable with theextension assembly 230 by conventional air and fluid tight means. Inembodiments, the canister inlet port 334 may contain a luer lock orother connector within the purview of those skilled in the art to securethe end of the extension assembly 230 with the canister inlet port 334.Canister inlet port 334 may be configured to receive a cap for use toprevent leakage of exudate and odor from the chamber 335 when thecollection canister 242 is separated from the control unit 246. Inalternate embodiments, the canister inlet port 334 is coupled to acanister inlet conduit (e.g., 250 shown in FIG. 2) in fluidcommunication with the dressing assembly.

In embodiments, the control unit 246 includes a suction pump 360, a pumpinlet conduit 372, a pump outlet conduit 362, a pressure sensor 340, anda pressure sensor conduit 352. Additionally, a first filter element 376and/or a second filter element 354 may be included. A first connectingchannel 378 may be included to provide fluid communication between thefirst filter element 376 and the suction port 374 located on thecanister top 336. A second connecting channel 356 may be included toprovide fluid communication between the second filter element 354 andthe pressure sensor port 396 located on the canister top 336.

Suction pump 360 may provide negative pressure produced by a pistondrawn through a cylinder. Suction pump 360 may be a peristaltic pump ora diaphragm pump. Suction pump 360 may be a manual pump or an automatedpump. The automated pump may be in the form of a portable pump, e.g., asmall or miniature pump that maintains or draws adequate and therapeuticvacuum levels. In one embodiment, the suction pump 360 is a portable,lightweight, battery-operated, DC motor-driven pump. A vibration dampingtape (not shown), e.g., visco-elastic damping tape, may be applied tothe outer surface of the suction pump 360 to reduce vibration and itsassociated noise. Suction pump 360 may be contained within its ownsub-housing (not shown), which may be formed substantially entirely ofmolded foam, e.g., used as a silencer to provide sound mitigation byreducing the sound energy of the expelled air during operation of thesuction pump 360, and may include a carbon loaded foam. Suction pump 360provides negative pressure within the chamber 335 of the collectioncanister 242 by drawing air through the suction port 374. Exhaust airfrom the suction pump 360 is vented through an exhaust port (not shown)via the pump outlet conduit 362. Pump outlet conduit 362 may be coupledto one or more filters (not shown) for filtering the exhaust air fromthe pump 360.

In embodiments, the pump inlet conduit 372 provides fluid communicationbetween the suction pump 360 and the suction port 374 located on thecanister top 336, when the control unit 246 and the collection canister242 are operablely coupled to each other. In alternate embodiments,first filter element 376 is disposed between the suction pump 360 andthe suction port 374. Pump inlet conduit 372 may be adapted to providefluid communication between the suction pump 360 and the first filterelement 376. First filter element 376 may include one or more filtersand is configured to substantially prevent entry of exudate into thesuction pump 360. In embodiments, the control unit 246 stops operationof the suction pump 360 when the first filter element 376 becomesoccluded. A variety of filters can be used for the first filter element376. In one embodiment, the first filter element 376 includes ahydrophobic filter that substantially prevents fluids from entering intothe suction pump 360 and potentially causing damage to electronics orpneumatic components.

Pressure sensor 340 is in fluid communication with the collectioncanister 242 to detect the vacuum level within the chamber 335 of thecollection canister 242. In embodiments, the pressure sensor 340generates an electrical signal that varies as a function of vacuum levelwithin the chamber 335, and the signal is communicated to the processor310. Logic associated with the pressure sensor 340 and the pump 360 mayreduce the speed of the pump 360 or stop operation of the pump 360 inresponse to the vacuum level detected by the pressure sensor 340. Anysuitable device capable of detecting pressure may be utilized for thepressure sensor 340, including, but not limited to, a pressure switch ora pressure transducer or transmitter:

In embodiments, the pressure sensor conduit 352 provides fluidcommunication between the pressure sensor 340 and the pressure sensorport 396 located on the canister top 336, when the control unit 246 andthe collection canister 242 are operablely coupled to each other. Inalternate embodiments, second filter element 354 is disposed between thepressure sensor 340 and the pressure sensor port 396. Pressure sensorconduit 352 may be adapted to provide fluid communication between thepressure sensor 340 and the second filter element 354. Second filterelement 354 may include one or more filters and is configured tosubstantially prevent entry of exudate into the pressure sensor 340. Avariety of filters can be used for the second filter element 354. In oneembodiment, the second filter element 354 includes a hydrophobic filterthat substantially prevents fluid contamination of the pressure sensor340.

In embodiments, the first connecting channel 378 provides fluidcommunication between the first filter element 376 and the suction port374, when the control unit 246 and the collection canister 242 areoperably coupled to each other. First connecting channel 378 may becoupled to a control suction port (not shown) located on the bottom sideof the control unit 246 and configured to engage with the suction port374 located on the canister top 336 when the control unit 246 and thecollection canister 242 are joined together. In embodiments, the secondconnecting channel 356 provides fluid communication between the secondfilter element 354 and the pressure sensor port 396, when the controlunit 246 and the collection canister 242 are operably coupled to eachother. Second connecting channel 356 may be coupled to a control unitpressure sensor port (not shown) located on the bottom side of thecontrol unit 246 and configured to engage with the pressure sensor port396 located on the canister top 336 when the control unit 246 and thecollection canister 242 are joined together.

Control unit 246 also includes a processor 310. In embodiments, theprocessor 310 is electrically coupled via a transmission line 341 to thepressure sensor 340 and electrically coupled via a transmission line 361to the suction pump 360. Processor 310 may include any type of computingdevice, computational circuit, or any type of processor or processingcircuit capable of executing a series of instructions that are stored ina memory (not shown) of the control unit 246. The series of instructionsmay be transmitted via propagated signals for execution by processor 310for performing the functions described herein and to achieve a technicaleffect in accordance with the present disclosure. Control unit 246 mayalso include a user interface (not shown).

Canister assembly 240 may also include a sensor 320. In embodiments, thesensor 320 is used to measure resistance, capacitance or voltage toprovide feedback to the processor 310 indicative of a condition. Inembodiments, an electric circuit 328 is electrically coupled via atransmission line 321 between the sensor 320 and the processor 310.Electric circuit 328 is configured to detect an electrical propertyassociated with the sensor 320 and may include various components.Although the electric circuit 328 is shown as a separate circuit in FIG.3, it may be incorporated into the sensor 320, the processor 310, orother component, e.g., a printed circuit board (not shown) associatedwith the processor 310.

Sensor 320 may include an electrode pair (e.g., 425A, 425B shown in FIG.4). Sensor 320 may include multiple electrode pairs. In embodiments, anychange in the resistance, capacitance or voltage feedback occurring whenthe electrodes are simultaneously in contact with exudate in thecollection canister 242 is used to indicate areplace-collection-canister condition or a full-collection-canistercondition (described later in this disclosure). Examples of sensor andelectric circuit embodiments are disclosed in commonly assigned U.S.patent application Ser. No. ______ filed on ______, 2009, entitled“SENSOR WITH ELECTRICAL CONTACT PROTECTION FOR USE IN FLUID COLLECTIONCANISTER AND NEGATIVE PRESSURE WOUND THERAPY SYSTEMS INCLUDING SAME”,the disclosure of which is herein incorporated by reference in itsentirety.

Referring to FIG. 4, an embodiment of the collection canister 242 of thecanister assembly 240 illustrated in FIG. 3 is shown and includes thecanister top 336, the chamber 335, which has length “L1”, the canisterinlet port 334, the suction port 374, and the pressure sensor port 396.The sensor 320 of FIG. 3 is shown as an electrode pair 425A, 425B inFIG. 4. In embodiments, an electric potential (or voltage) is applied tothe electrodes 425A, 425B. When a voltage is supplied and the electrodes425A, 425B are simultaneously in contact with an ionic fluid, e.g.,exudate, electric current flows via an electro-chemical reaction thatoccurs between the ions in the fluid and the electrically polarizedelectrodes 425A, 425B.

In embodiments, one or more electrode pairs (e.g., 425A, 425B shown inFIG. 4) is coupled to an electric circuit (e.g., 328 shown in FIG. 3),which is configured to detect an electrical properly associated with theelectrode pair(s). In embodiments, a measurement of the change involtage across the electrode pair(s) as a result from the flow ofcurrent is used to activate an indicator (not shown) as notification tothe user of a condition. For example, an indicator may be activated tonotify the user that the collection canister 242 is full, which may bereferred to as the full-collection-canister condition. An indicator maybe activated to notify the user that it is time to replace thecollection canister 242, which may be referred to as thereplace-collection-canister condition. The occurrence of areplace-collection-canister condition indicates that a volume of exudate(generally being less than the volume of the chamber 355) has beencollected. User notification of a replace-collection-canister conditionmay thus provide some flexibility to the user in the timing of thereplacement or emptying of the collection canister 242, by allowing anadditional time period of operation before the volume of the collectedexudate reaches the maximum volume capacity of the chamber 355.

Referring to FIG. 5, the bottom side of the canister top 336 illustratedin FIG. 4 is shown and includes the canister inlet port 334, the suctionport 374, the pressure sensor port 396 and the two electrodes 425A,425B. Additionally, a side wall 580 with a recessed portion 584 isincluded. In embodiments, the suction port 374, the pressure sensor port396 and the two electrodes 425A, 425B are disposed to the interior ofthe side wall 580. Side wall 580 is adapted to provide engagement of thecanister top 336 with the upper end of the peripheral wall of thechamber 335 and may help to provide sealing of the canister top with thechamber 335. In one embodiment, the peripheral edge of the recessportion 584 is shaped to partly encircle the canister inlet port 334.The relative positions, size and/or shape of the side wall 580, thecanister inlet port 334, the suction port 374, the pressure sensor port396 and the two electrodes 425A, 425B may be varied from an embodimentdepicted in FIG. 5.

Canister top 336 may be fabricated from plastic materials by moldingtechniques. Canister top 336 may be secured to the open top of thecollection canister 242 by friction fit between the side wall 580 andthe peripheral wall of the chamber 335. Side wall 580 may be fixablyattached to the upper end of the peripheral wall of the chamber 335,e.g., using an ultrasonic welding process.

In FIGS. 6 through 8, another embodiment of a canister top of acollection canister (e.g., 242 shown in FIG. 3) is shown. Canister top636 includes a canister inlet port 634, a suction port 674 and apressure sensor port 696. In embodiments, the canister top 636 may alsoinclude one or more electrode pairs, e.g., electrode pair 425A, 425B, asdescribed above. Canister top 636 includes a side wall 680, an outersealing rib “R1” and an isolating rib “R2”. In embodiments, the canistertop 636 may include support elements 612 that are configured to providesupport for a filter membrane (e.g., 760 shown in FIG. 7).

As shown in FIGS. 6 and 8, the outer sealing rib “R1” and the isolatingrib “R2” define two chambers, “A1” and “A2”, which are pneumaticallyisolated from each other by the isolating rib “R2”. In embodiments, thefirst chamber “A1” includes the pressure sensor port 696 and the secondchamber “A2” includes the suction port 674. In alternate embodiments,the first chamber “A1” includes the suction port 674 and the secondchamber “A2” includes the pressure sensor port 696. Although the sensorport 696 and the suction port 674 are shown and described as included inpneumatically isolated chambers, it is contemplated herein that thepressure sensor port 696 and the suction port 674 may be included insame chamber.

In embodiments, the exterior wall of the outer sealing rib “R1”, orportion thereof, is disposed directly adjacent to or substantiallyadjacent to the side wall 680. In embodiments, the isolating rib “R2”,or portion thereof, is spaced apart from the interior wall of the outersealing rib “R1”. In the illustrated embodiment, the first chamber “A1”is an elongated pathway that extends approximately around the perimeterof the canister top and is formed between the isolating rib “R2” and theouter sealing rib “R1”. Although the first chamber “A1” is shown anddescribed as an elongated pathway including the pressure sensor port696, it is contemplated herein that the first chamber “A1” may includemultiple pathways in fluid communication with the pressure sensor port696.

Referring to FIG. 7, the canister top 636 of FIG. 6 is shown andincludes a filter membrane 760 disposed to the interior of the side wall680. Filter membrane 760 may include a micro-pore filter membrane. Inembodiments, the filter membrane 760 is cut to the profile of the outersealing rib “R1”. Filter membrane 760 is attached to the isolating rib“R2” and the outer sealing rib “R1” and may be attached to the supportelements 612. Filter membrane 760 may be attached to the outer sealingrib “R1” and the isolating rib “R2” by adhesive such as UV cure,catalyzed, vulcanized or other type, or welded by ultrasonic or radiofrequency means.

Filter membrane 760 generally allows air flow while substantiallypreventing liquid and bacterial passage therethrough. In embodiments,the filter membrane 760 allows air flow to the suction pump (e.g., 360shown in FIG. 3) and allows the vacuum level at the collection canisterto be monitored using a pressure sensor (e.g., 340 shown in FIG. 3) influid communication with the collection canister through the filtermembrane 760. Negative pressure wound therapy systems including acollection canister having a canister top in accordance with embodimentsof the present disclosure may be capable of accurate measurement ofvacuum levels within the collection canister and capable of providingnegative pressure therapy for varied orientations of the collectioncanister.

Referring to FIG. 9, another embodiment of a collection canister 942 isshown and includes a chamber 935 to collect fluids and a canister top936 disposed over the chamber 935. The canister top 936 includes abottom side facing into the chamber 935. The bottom side of the canistertop 936 includes first and second ribs, “R1” and “R2”, disposed thereon,and a side wall 680, as described above. A filter membrane 960 isattached to the first and second ribs, “R1” and “R2”. Canister top 936also includes a first port 974 to communicate with the chamber 935 and apressure source external to the chamber, and a second port tocommunicate with the chamber 935 and a sensor external to the chamber935. The first port is in fluid communication with a first area “A1”,which is bounded by the filter membrane 960, the first and second ribs,“R1” and “R2”, and the bottom side of the canister top 936. The secondport is in fluid communication with a second area“A2”, which is boundedby the filter membrane 960, the second rib “R2” and the bottom side ofthe canister top 936. In embodiments, the canister top 936 also includesa third port 934 to introduce the fluids into the chamber 935.

Referring to FIGS. 10 through 12, the canister top 936 of the collectioncanister 942 of FIG. 9 is shown. Canister top 936 includes the side wall680 shown in FIGS. 6 through 8. Canister top 936 includes a first port974 and a second port 996 and may include a third port 934, as describedabove. In embodiments, the canister top 936 may include one or moreelectrode pairs, e.g., electrode pair 925A, 925B. Electrode pair 925A,925B shown in FIG. 9 is substantially similar to the electrode pair425A, 425B of the collection canister 242 illustrated in FIG. 4 andfurther description thereof is omitted in the interests of brevity.

Canister top 936 also includes a first rib “R1” and a second rib “R2”.As shown in FIGS. 10 and 12, the first rib “R1” and the second rib “R2”define two areas, “A1” and “A2”, which are pneumatically isolated fromeach other by the second rib “R2”. As shown in FIG. 11, the filtermembrane 960 is cut to the profile of the first rib “R1”. Filtermembrane 960 may include any suitable material capable of allowing airflow while substantially preventing liquid and bacterial passagetherethrough. Filter membrane 960 may include a micro-pore filtermembrane. In embodiments, the canister top 936 may include supportelements 912 that are configured to provide support for the filtermembrane 960. In embodiments, the filter membrane 960 is attached to thefirst rib “R1” and the second rib “R2” and may be attached to thesupport elements 912. The relative positions, size and/or shape of thefirst rib “R1”, the second rib “R2” and the support elements 912 may bevaried from an embodiment depicted in FIGS. 10 through

Although embodiments of the present disclosure have been described indetail with reference to the accompanying drawings for the purpose ofillustration and description, it is to be understood that the inventiveprocesses and apparatus are not to be construed as limited thereby. Itwill be apparent to those of ordinary skill in the art that variousmodifications to the foregoing embodiments may be made without departingfrom the scope of the disclosure.

1. A fluid collection canister, comprising: a chamber to collect fluids; a canister top disposed over the chamber, the canister top including a bottom side facing into the chamber, the bottom side including first and second ribs disposed thereon; a filter membrane attached to the first and second ribs, a first port located on the canister top to communicate with the chamber and a pressure source external to the chamber; a second port located on the canister top to communicate with the chamber and a sensor external to the chamber; and wherein the first port is in fluid communication with a first area, the first area bounded by the filter membrane, the first and second ribs and the bottom side of the canister top, and wherein the second port is in fluid communication with a second area, the second area bounded by the filter membrane, the second rib and the bottom side of the canister top.
 2. The fluid collection canister of claim 1, wherein the filter membrane is cut to a profile of the first rib.
 3. The fluid collection canister of claim 1, wherein the filter membrane includes a micro-pore filter membrane.
 4. The fluid collection canister of claim 1, wherein the first and second areas are pneumatically isolated from each other by the second rib.
 5. The fluid collection canister of claim 1, further comprising a third port to introduce the fluids into the chamber.
 6. The fluid collection canister of claim 1, further comprising a side wall to provide engagement of the canister top with an upper end of a peripheral wall of the chamber.
 7. The fluid collection canister of claim 6, wherein at least a portion of the first rib is disposed adjacent to the side wall.
 8. The fluid collection canister of claim 1, wherein the sensor is a pressure sensor.
 9. A portable negative pressure wound therapy system, comprising: a dressing assembly for positioning over a wound to apply a negative pressure to the wound; and a canister assembly including: a control unit; a vacuum source disposed in the control unit; a pressure sensor in communication with the control unit; and a collection canister including: a chamber to collect wound fluids from the dressing assembly; a canister top disposed over the chamber, the canister top including a bottom side facing into the chamber, the bottom side including first and second ribs disposed thereon; an inlet port in fluid communication with the dressing assembly to introduce the wound fluids from the dressing assembly into the chamber; a suction port located on the canister top to communicate with the chamber and the vacuum source; a pressure sensor port located on the canister top to communicate with the chamber and the pressure sensor; and a filter membrane attached to the first and second ribs, wherein the pressure sensor port is in fluid communication with a first chamber, the first chamber bounded by the filter membrane, the first and second ribs and the bottom side of the canister top, and wherein the suction port is in fluid communication with a second chamber, the second chamber bounded by the filter membrane, the second rib and the bottom side of the canister top.
 10. The portable negative pressure wound therapy system of claim 9, wherein the control unit monitors and controls a negative pressure within the collection canister.
 11. The portable negative pressure wound therapy system of claim 9, wherein the first and second chambers are pneumatically isolated from each other by the second rib. 